Morphological changes of cerebral arteries in a canine double hemorrhage model.

Cerebral vasospasm is a major cause of morbidity and mortality in patients suffering from subarachnoid hemorrhage (SAH). Despite numerous studies, the pathogenesis of this deadly disorder is not clearly understood. Alterations in endothelial cells are a distinct morphological feature of cerebral vasospasm and some recent studies suggest that apoptosis might play a role in the cells' death. The goal of the present study is to examine the time course of apoptosis in endothelial cells of spastic cerebral arteries following experimental subarachnoid hemorrhage. Fifteen dogs were used in the present study. Twelve of them were divided into three groups (four per group) and subjected to a double-hemorrhage method of SAH. Following SAH, groups were sacrificed respectively on days 3, 5, and 7. Three dogs served as controls without blood injection. The basilar arteries were studied with the transmission electron microscopy and with angiography. Angiographic vasospasm began on day 3 and peaked on day 7. In morphologic studies, control dogs did not demonstrate apoptotic-like changes in endothelial cells of the basilar arteries. Beginning with day 3, apoptotic-like changes were noted in endothelial cells and consisted of condensation of peripheral nuclear chromatin, blebbing of the cell membrane, and condensation of the cytoplasm. Such changes progressed with time and were maximally developed by day 7. This is the first study that demonstrates the time course of apoptotic-like changes in the endothelial cells in the vasospastic basilar artery. Apoptosis might play an important role in the pathogenesis of vasospasm.